Researchers unveil the Einstein Telescope: A Journey of Physics to an Immense Glory

Fri, 20 May 2011 21:01:19 +0100

Researchers have drawn up plans for the next-generation gravitational-wave observatory that will be 100 times more sensitive than current instruments. The Einstein Telescope, which is estimated to cost around €790m and be complete by 2025, will seek to directly detect gravitational waves and attempt to work out their origin and nature. It will differ from existing gravitational-wave detectors in being built underground.

Researchers will now begin carrying out a detailed technical design for the Einstein Telescope, which is expected to be complete by 2017, as well as selecting its location. The telescope is one of seven projects recommended by the Astroparticle European Research Area (ASPERA) network, funded by the European Commission, the CERN particle-physics lab and 17 countries including Germany, Russia and the UK.

Gravitational waves are ripples in the fabric of space–time that Einstein's general theory of relativity predicts ought to pervade the universe. The Einstein Telescope – known as a third-generation gravitational-wave observatory – would be similar in design to existing labs such as the US-based LIGO gravitational-wave observatory in Hanford, Washington, and Livingston, Louisiana.

LIGO works by having two 4 km long interferometers at 90° to each other in which a laser beam is split and sent down each arm. The beams then bounce off test masses at the end of each arm and return to their starting point, where they interfere with one another. Any passing gravitational wave will make one arm slightly longer and the other slightly shorter, thereby changing the interference pattern in a measurable way.

Going underground

The Einstein Telescope will study the entire range of gravitational-wave frequencies – from 1 Hz to 10 kHz – from astronomical sources that can be measured on Earth. The observatory will be built underground at a depth of about 100–200 m and will consist of three underground detectors, each linked by two 10 km long interferometer arms.

One of the interferometers will detect low-frequency gravitational-wave signals from 2 to 40 Hz, while the other will detect the higher-frequency signals. "The fact that the Einstein Telescope will be underground allows us to extend the sensitive window down to lower frequencies, such as those below 10 Hz," says Andreas Freise from the University of Birmingham in the UK, who leads the optical design of the telescope. "Many gravitational-wave signals from, for example, black holes crashing into each other, will have a significant signature in that range."

LIGO is currently being upgraded to Advanced LIGO, which will make it 10 times more sensitive. According to Freise, physicists expect Advanced LIGO to make the first direct detection of gravitational waves, but as the Einstein Telescope will be a further 10 times more sensitive, it will be better placed to estimate the origins of gravitational waves and give information about the local gravitational environment around them.

New method confirms Dark Energy: Einstein was Right!

Fri, 20 May 2011 19:48:23 +0100

First results from a major astronomical survey using a cutting-edge technique appear to have confirmed the existence of mysterious dark energy!

Dark energy makes up some 74% of the Universe and its existence would explain why the Universe appears to be expanding at an accelerating rate.

The finding was based on studies of more than 200,000 galaxies.

Scientists used two separate kinds of observation to provide an independent check on previous dark energy results.

Two papers by an international team of researchers have been accepted for publication in the Monthly Notices of the Royal Astronomical Society journal.

One type of observation used by the astronomers involves measuring a pattern in how galaxies are distributed in space. This pattern is known by the term "baryon acoustic oscillations".

The second type of observation involves measuring how quickly clusters of galaxies have formed over time. Both of these techniques confirmed the existence of dark energy and the acceleration in the expansion of the Universe.

The concept of dark energy was first invoked in the late 1990s by studying the brightness of distant supernovas - exploding stars.

Einstein was right

To explain why the expansion of the Universe was speeding up, astronomers had to either rewrite Albert Einstein's theory of gravity or accept that the cosmos was filled with a novel type of energy.

"The action of dark energy is as if you threw a ball up in the air, and it kept speeding upward into the sky faster and faster," said co-author Dr Chris Blake of the Swinburne University of Technology in Melbourne, Australia.

"The results tell us that dark energy is a cosmological constant, as Einstein proposed. If gravity were the culprit, then we wouldn't be seeing these constant effects of dark energy throughout time."

The latest findings have come from a galaxy survey project called WiggleZ, which began in 2006 and finished this year. WiggleZ used data from Nasa's Galaxy Evolution Explorer (Galex) space telescope and the Anglo-Australian Telescope on Siding Spring Mountain in Australia.

The survey mapped the distribution of galaxies in an unprecedented volume of the Universe, looking eight billion years back in time - more than half the age of the Universe.

Cosmologist Bob Nicholl, who was not involved with the research, told BBC News: "This is a major step forward. These guys are serious, major scientists and we've been waiting for this result for some time.

The professor of astrophysics at Portsmouth University, UK, added: "It's re-confirmation of dark energy, it gives us another data point to fit our theories around and it shows us the way to the future. More astronomers are going to be doing this in years to come."

While dark energy makes up about 74% of the Universe, dark matter - which does not reflect or emit detectable light - accounts for 22%. Ordinary matter - gas, stars, planets and galaxies - makes up just 4% of the cosmos.

However, despite scientists being able to infer the existence of dark energy and dark matter, these phenomena still elude a full explanation.

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Researchers unveil the Einstein Telescope: A Journey of Physics to an Immense Glory

Going underground

New method confirms Dark Energy: Einstein was Right!